Before personnel, irrespective of their type (e.g., Federal employee, contractor, etc.), may Enter on Duty (EOD), a background investigation must be initiated. These investigations fit into two categories:
Investigations for Suitability
A suitability investigation is an inquiry into a person's identifiable character traits and conduct sufficient to make a determination whether an individual's employment or continued employment would or would not protect the integrity or promote the efficiency of the service.
This type of investigation is for positions that are considered risk-designated, i.e., Low, Moderate, or High-Risk, and individuals do not have nor are they eligible for a “clearance.”
Investigations for Security Clearances (or Clearance Eligibility)
This type of investigation is an in-depth inquiry into an individual's loyalty, character, trustworthiness and reliability to ensure that he or she is eligible for access to national security information (NSI). Not all positions in this category require access to NSI, and will only be granted to those which do where there is a need-to-know.
The Office of Security (OSY) PerSec program, is the Department of Commerce's primary authority to adjudicate background investigations necessary to grant a clearance to individuals holding a position requiring access to NSI.
Once favorably adjudicated and based on their investigation type and need-to-know, an individual may be granted access to NSI at the Secret or Top Secret level and, for individuals in positions designated as Special-Sensitive, Sensitive Compartmented Information (SCI).
Addition to being necessary to EOD, periodic reinvestigations are required at pre-determined intervals for individuals eligible for access to NSI whether or not they have a clearance, and for most risk-designated positions.
 35 U.S.C. §3(b)(5), “National security positions.—The [Under Secretary of Commerce for Intellectual Property and Director of the United States Patent and Trademark Office], in consultation with the Director of the Office of Personnel Management, shall maintain a program for identifying national security positions and providing for appropriate security clearances, in order to maintain the secrecy of certain inventions, as described in section 181 [Secrecy of certain inventions and withholding of patent], and to prevent disclosure of sensitive and strategic information in the interest of national security.”